When data is to be communicated between two end-points over a network for telecommunication involving at least one radio link, the end-points need to know which rate they should use when communicating the data so that they can prepare and set up their communication equipment accordingly, which is commonly referred to as “rate adaptation”, provided that the data rate is adaptive and can be selected. Throughout this disclosure, the term “data rate” is used to denote how much data to communicate per time unit, which may be expressed as information bits per second, known as the bitrate. Other rates which are representative for the data rate may also be used in this context such as frame rate or block rate.
Some non-limiting but illustrative examples of data communication include voice and video calls, streaming of audio and visual content e.g. music and video, on-line games, web browsing, file downloads, exchange of information e.g. in the form of files, images and notifications, and so forth, i.e. any kind of data that can be communicated between end-points over a telecommunication network. It is common that the end-points themselves initially negotiate and agree on which data rate to use before the communication begins, depending on their respective capabilities.
Thus, in order to communicate the data both end-points must be able to use the same encoding and communication schemes which may be determined by exchanging their capabilities with each other in the negotiation. In this case the rate adaptation is controlled by the end-points. It is also possible that the rate adaptation is controlled by an intermediate network node which selects a suitable data rate for the forthcoming data communication and sends a recommendation or instruction to at least the data sending node to use this data rate.
FIG. 1 illustrates a communication scenario where data is communicated from one wireless device D1 to another wireless device D2 over an intermediate communication network 100, the devices D1, D2 thus being two end-points which can be generally referred to as a data sending node and a data receiving node, respectively. The data is transmitted over a first radio link from the data sending node D1 to its serving network node 102, typically a base station or the equivalent. The data is then transported over various nodes of the network 100 until another network node 104 serving the data receiving node D2 finally transmits the data over a second radio link to D2. The network nodes 102 and 104 may belong to the same radio access network or to separate radio access networks.
In general, it is mostly desirable to use as high data rate as possible in order to achieve good or at least satisfactory service performance in the data communication. However, if the data rate is too high, a radio link involved in the data communication may not have sufficient capacity and/or quality to transport the data with such high rate, particularly when the radio link is shared by multiple communications and the current traffic load is high, which typically results in deteriorated service performance due to interruptions of the data flow. It has therefore been proposed to employ rate adaptation for a communication of data involving at least one radio link where a suitable data rate is selected which is adapted to the link quality and/or the current traffic load on that radio link which both typically fluctuate over time.
An example of the above is illustrated in FIG. 1 where the network node 102 determines a suitable data rate to recommend for the data communication depending on the current state of the first radio link in terms of load and/or quality. The network node 102 then signals the recommended data rate to the data sending node D1, as illustrated by an action 1:1. Since two radio links are involved in this data communication, it may be desirable to adapt the recommended data rate to both these links by not exceeding the rate allowed by the “slowest” one of the first and second radio links, in order to achieve a smooth end-to-end data communication, e.g. without getting interruptions at the data receiving node D2. Another action 1:2 illustrates that the network node 104 may thus signal a recommended data rate to the data receiving node D2 as well.
US 2012/0086767 A1 discloses how a frame rate of a video call can be adapted based on link quality of one or both of two telecommunication devices where the rate adaptation is controlled by an intermediate server of a telecommunications service provider.
It is however a problem that the recommended data rate may still not be optimal, suitable or even possible to use in a data communication between end-points due to various limitations experienced by one or both of the communicating end-points, particularly when a shared radio link is used which is thus utilized for more than one communication. Therefore, the data communication may be executed with less performance and/or efficiency than what would otherwise be possible to achieve under the prevailing circumstances. US 2012/0086767 A1 does not address the scenario with shared radio link.